Semiconductor device

Abstract

A semiconductor device includes a lead frame, a transistor, and an encapsulation resin. The lead frame includes a drain frame, a source frame, and a gate frame. The drain frame includes drain frame fingers. The source frame includes source frame fingers. The drain frame fingers and the source frame fingers are alternately arranged in a first direction and include overlapping portions as viewed from a first direction. In a region where each drain frame finger overlaps the source frame fingers as viewed in the first direction, at least either one of the drain frame fingers and the source frame fingers are not exposed from the back surface of the encapsulation resin.

The invention claimed is: 
     
       1. A semiconductor device comprising:
 a lead frame; 
 a transistor including a plurality of drain electrode pads, a plurality of source electrode pads, and a gate electrode pad on one surface, the plurality of drain electrode pads, the plurality of source electrode pads, and the gate electrode pad facing a front surface of the lead frame and being connected to the lead frame; and 
 an encapsulation resin that has a rectangular-plate shape and encapsulates the transistor and the lead frame so that a part of the lead frame is exposed from a back surface of the encapsulation resin, wherein 
 the lead frame includes a drain frame electrically connected to the plurality of drain electrode pads, a source frame electrically connected to the plurality of source electrode pads, and a gate frame electrically connected to the gate electrode pad, 
 the drain frame includes a plurality of drain frame fingers, 
 the plurality of drain frame fingers are spaced apart from each other in a first direction, extended in a second direction that is orthogonal to the first direction in a plan view, and each one of the plurality of the drain frame fingers is connected to a respective one of the plurality of drain electrode pads, 
 the source frame includes a plurality of source frame fingers, 
 the plurality of source frame fingers are spaced apart from each other in the first direction, extended in the second direction, and each one of the plurality of the source frame fingers is connected to a respective one of the plurality of source electrode pads, 
 each one of the plurality of the drain frame fingers and each one of the plurality of the source frame fingers are alternately arranged in the first direction and overlap each other as viewed in the first direction, 
 in a region where the plurality of drain frame fingers and the plurality of source frame fingers overlap one another as viewed in the first direction, at least either one of the plurality of drain frame fingers and the plurality of source frame fingers are not exposed from the back surface of the encapsulation resin, and 
 in the region where the plurality of drain frame fingers and the plurality of source frame fingers overlap one another as viewed in the first direction, either one of the plurality of drain frame fingers and the plurality of source frame fingers are exposed from the back surface of the encapsulation resin, and the other one of the plurality of drain frame fingers and the plurality of source frame fingers are not exposed from the back surface of the encapsulation resin. 
 
     
     
       2. The semiconductor device according to  claim 1 , wherein in the region where the plurality of drain frame fingers and the plurality of source frame fingers overlap one another as viewed in the first direction, the plurality of drain frame fingers are exposed from the back surface of the encapsulation resin, and the plurality of source frame fingers are not exposed from the back surface of the encapsulation resin. 
     
     
       3. The semiconductor device according to  claim 2 , wherein
 the drain frame includes a plurality of drain terminals formed on one side of the encapsulation resin in the second direction and spaced apart from each other in the first direction, 
 the source frame includes a plurality of source terminals formed on another side of the encapsulation resin in the second direction and spaced apart from each other in the first direction, and 
 the transistor is located towards the plurality of source terminals in the second direction. 
 
     
     
       4. The semiconductor device according to  claim 3 , wherein a length of each one of the plurality of source frame fingers is less than a length of each one of the plurality of drain frame fingers in the second direction. 
     
     
       5. The semiconductor device according to  claim 3 , wherein
 each one of the plurality of drain frame fingers includes a first section located towards the plurality of drain terminals and a second section continuously extending from the first section towards the plurality of source terminals, 
 the first section is located closer to the plurality of drain terminals than a distal end of each one of the plurality of source frame fingers, and 
 a width of the first section is greater than a width of the second section. 
 
     
     
       6. The semiconductor device according to  claim 5 , wherein
 the first section includes a base that is continuous with the second section and flanges that project from opposite sides of the base in the first direction, and 
 a thickness of the flanges is less than a thickness of the base. 
 
     
     
       7. The semiconductor device according to  claim 3 , wherein a portion of each one of the plurality of source frame fingers overlapped with each one of the plurality of drain frame fingers as viewed in the first direction has a thickness that is less than a maximum thickness of each one of the plurality of drain frame fingers. 
     
     
       8. The semiconductor device according to  claim 3 , wherein
 the source frame includes a source coupling portion that couples the plurality of source frame fingers, and 
 the plurality of source frame fingers extend in the second direction from the source coupling portion and are not exposed from the back surface of the encapsulation resin. 
 
     
     
       9. The semiconductor device according to  claim 8 , wherein a thickness of the source coupling portion is less than a thickness of each one of the plurality of drain frame fingers. 
     
     
       10. The semiconductor device according to  claim 3 , wherein a distal portion of each one of the plurality of drain frame fingers located toward the plurality of source terminals is not exposed from the back surface of the encapsulation resin in the second direction. 
     
     
       11. The semiconductor device according to  claim 10 , wherein a thickness of the distal portion of each one of the plurality of drain frame fingers located toward the plurality of source terminals is less than a maximum thickness of each one of the plurality of drain frame fingers in the second direction. 
     
     
       12. The semiconductor device according to  claim 10 , wherein
 each one of the plurality of drain electrode pads is supported by a corresponding one of the plurality of drain frame fingers at a part of each one of the plurality of drain frame fingers located toward the plurality of source terminals including the distal portion, and 
 the part of each one of the plurality of drain frame fingers that supports each one of the plurality of drain electrode pads includes a portion exposed from the back surface of the encapsulation resin. 
 
     
     
       13. The semiconductor device according to  claim 12 , wherein the part of each one of the plurality of drain frame fingers that supports each one of the plurality of drain electrode pads has a thickness that is greater at a portion located towards the plurality of drain terminals than the distal portion. 
     
     
       14. The semiconductor device according to  claim 3 , wherein
 the drain frame includes a drain coupling portion that couples the plurality of drain frame fingers in the first direction, and 
 a width of the drain coupling portion in the second direction is greater than a width of each one of the plurality of drain frame fingers in the first direction. 
 
     
     
       15. The semiconductor device according to  claim 14 , wherein a thickness of the drain coupling portion at an end located towards the plurality of source terminals is less than a thickness of the drain coupling portion at a part located towards the plurality of drain terminals. 
     
     
       16. The semiconductor device according to  claim 3 , wherein at least one of a tie bar portion of the drain frame and a tie bar portion of the source frame is not exposed from the back surface of the encapsulation resin. 
     
     
       17. The semiconductor device according to  claim 16 , wherein a thickness of at least one of the tie bar portion of the drain frame and the tie bar portion of the source frame is less than the thickness of each one of the plurality of drain frame fingers. 
     
     
       18. The semiconductor device according to  claim 16 , wherein
 the drain frame includes a drain coupling portion that couples the plurality of drain frame fingers in the first direction, and 
 the tie bar portion of the drain frame includes a first tie bar portion arranged on the drain coupling portion and a second tie bar portion arranged on one of the plurality of drain frame fingers. 
 
     
     
       19. The semiconductor device according to  claim 3 , wherein the gate frame is arranged at the other side of the encapsulation resin in the second direction and at one end of the encapsulation resin in the first direction. 
     
     
       20. The semiconductor device according to  claim 19 , wherein
 the gate frame includes a gate frame finger that is adjacent to one of the plurality of source frame fingers in the first direction, 
 the gate frame finger includes a portion that overlaps the plurality of drain frame fingers as viewed in the first direction, and 
 the portion of the gate frame finger that overlaps the plurality of drain frame fingers as viewed in the first direction is not exposed from the back surface of the encapsulation resin. 
 
     
     
       21. The semiconductor device according to  claim 20 , wherein a thickness of the portion of the gate frame finger that overlaps each one of the plurality of drain frame fingers as viewed in the first direction is less than a thickness of each one of the plurality of drain frame fingers. 
     
     
       22. The semiconductor device according to  claim 21 , wherein a length of the gate frame finger is shorter than a length of each one of the plurality of source frame fingers in the second direction. 
     
     
       23. The semiconductor device according to  claim 20 , wherein one of the plurality of drain frame fingers arranged at an end in the first direction faces the gate frame finger in the second direction and has a shorter length than another one of the plurality of drain frame fingers in the second direction. 
     
     
       24. The semiconductor device according to  claim 3 , wherein a distal portion of each one of the plurality of source frame fingers is located closer to the plurality of source terminals than an end of each of the plurality of source electrode pads located closer to the plurality of drain terminals. 
     
     
       25. The semiconductor device according to  claim 1 , wherein each one of the plurality of drain electrode pads and each one of the plurality of source electrode pads are alternately arranged in the first direction. 
     
     
       26. The semiconductor device according to  claim 25 , wherein a distance between adjacent ones of the plurality of drain electrode pads in the first direction is equal to a distance between adjacent ones of the plurality of source electrode pads in the first direction. 
     
     
       27. The semiconductor device according to  claim 25 , wherein
 one of the plurality of drain electrode pads and the gate electrode pad are arranged at one end of the transistor in the first direction, 
 the one of the plurality of drain electrode pads and the gate electrode pad that are arranged at the end of the transistor are aligned in the second direction, and 
 the one of the plurality of drain electrode pads and the gate electrode pad arranged at the end of the transistor each have a length that is less than a length of the other ones of the plurality of drain electrode pads in the second direction.